At least two people were killed when a section of São Paulo’s Arena Corinthians, the venue scheduled to host the opening ceremony for next summer’s World Cup, collapsed on Wednesday. A third person is reportedly in serious condition at a local hospital. A fire department official had stated previously that three people had died, reports to the Associated Press.

A 114-foot-tall crane, reportedly Brazil’s largest, crashed down on the rear of the stadium as it hoisted one of the final pieces up toward the roof. The arena, known locally as Itaquerão, was reportedly 94 percent complete before the collapse. The two people killed are all thought to be construction workers, FIFA said in a statement.

Rescue teams are checking the damaged portion to see if there are more victims. Mauro Lopes, the fire department head, said there may be more casualties but added the toll would have been far worse had the accident not fallen during lunchtime, when there are fewer construction workers on site.

In a brief statement, Corinthians, the football club that will eventually move into the new stadium, said: “The board of Sport Club Corinthians Paulista hereby deeply regret the accident earlier in Corinthians Arena. No other information at this time.” Work was immediately halted on all parts of the stadium, though it wasn’t yet clear if the crane collapse would delay the 70,000-seat stadium’s opening.

Brazil has openly admitted it’s struggling to finish all 12 venues—blaming construction problems and delays caused by public protests about the wealth being spent on the preparations—within timelines requested by FIFA.